Question

    ‘X’ and ‘Y’ are capable of finishing a work in 9

    days and 12 days respectively. They worked together for 3 days. Find the number of days ‘Y’ alone would take to complete the leftover work.
    A 2 days Correct Answer Incorrect Answer
    B 7 days Correct Answer Incorrect Answer
    C 4 days Correct Answer Incorrect Answer
    D 5 days Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the total work be 36 units (LCM of 9 and 12)

    Efficiency of ‘X’ = 36 ÷ 9 = 4 units/day

    Efficiency of ‘Y’ = 36 ÷ 12 = 3 units/day

    Work done by ‘X’ and ‘Y’ together in 3 days = 3 × (4 + 3) = 21 units

    Remaining work = 36 – 21 = 15 units

    Time taken by ‘Y’ to finish the remaining work = 15 ÷ 3 = 5 days

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